What happened
On a night return flight from Yarmouth, Nova Scotia, to Grand Manan, New Brunswick, a Piper PA-31-310 experienced a significant power loss during its final approach. The pilot, flying under visual flight rules (VFR) in marginal weather, was attempting a second approach after low clouds and fog obscured the airport lighting during his first attempt.
While flying at approximately 1,000 feet above sea level, the pilot noticed a drop in manifold pressure on the left engine and an increasing need for right rudder to maintain directional control. In an effort to reduce drag from the windmilling propeller, the pilot feathered the left engine. However, following the feathering, the aircraft failed to accelerate or climb despite the application of full power to the remaining engine. The aircraft entered a shallow descent into a fog layer, eventually striking trees and the ground. The impact and a subsequent fire destroyed the aircraft. The pilot sustained serious injuries but managed to escape the wreckage before being located by a search team.
The investigation
The investigation focused on the aircraft's performance following the engine failure and the pilot's decision-making process. Investigators examined the wreckage, noting that the left propeller was in the feathered position at impact and that the right engine was producing substantial power, as evidenced by broken trees.
While the aircraft's weight and center of gravity were within limits, the investigation looked into the possibility of fuel exhaustion. Although the pilot believed sufficient fuel remained, the investigation noted that based on estimated consumption, the possibility of exhausting the outboard tanks could not be ruled out. Furthermore, the investigation analyzed the aircraft's single-engine climb performance, which, according to manufacturer calculations, should have been sufficient to maintain altitude if proper procedures had been followed.
Findings
- The left engine lost power for undetermined reasons.
- The pilot was conducting the approach at a low airspeed of approximately 80 KIAS, which was 20 knots below the recommended approach speed and below the best single-engine climb speed.
- The low altitude and low airspeed left the pilot with no time to analyze the engine malfunction before the necessity of feathering the engine forced a commitment to a single-engine overshoot.
- The pilot did not follow the full emergency procedures outlined in the Pilot Operating Handbook (POH) following the engine failure.
- The aircraft failed to accelerate or climb after the left engine was feathered, for reasons that could not be determined.